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TT: Fachverband Tiefe Temperaturen

TT 12: Fluctuations and Noise

TT 12.6: Vortrag

Montag, 18. März 2024, 16:15–16:30, H 3007

Noise measurements in four-terminal quantum wire interferometer — •Birkan Düzel¹, Olivio Chiatti¹, Christian Riha¹, Sven S. Buchholz¹, Dirk Reuter², Andreas D. Wieck³, and Saskia F. Fischer^1,4 — ¹Novel Materials Group,Humboldt-Universität zu Berlin,10099 Berlin, Germany — ²Optoelektronische Materialien undBauelemente, Universität Paderborn,33098 Paderborn, Germany — ³Angewandte Festkörperphysik,Ruhr-Universität Bochum,44780 Bochum, Germany — ⁴Center for the Science of Materials Berlin, 12489 Berlin, Germany

Quantum ring structures can be used to investigate interference effects of electrons as a result of phase-coherent transport. Voltage noise measurements are performed using the cross-correlation technique in an etched quantum ring structure based on Al_0.35Ga_0.65As/GaAs at temperatures of 4.2 K. In thermal equilibrium the measured two-terminal voltage noise depends on the detail of the contact configuration in these multiply-connected quantum wire ring structures [1,2]. Here, we investigate and discuss all noise contributions in various contact configurations and compare these with the calculated thermal noise according to the Johnson-Nyquist formula S_V=4 k_B T R, as determined from the four-terminal conductance measurements of the respective contact configuration. Aharonov-Bohm magneto-resistance oscillations observed at 15 mK prove quantum interference in the ring structure.

[1] C. Riha et al., Appl. Phys. Lett. 117, 063102 (2020).

[2] B. Düzel et al., accepted/to be published in 2023 International

Conference on Noise and Fluctuations (ICNF), IEEE.

Keywords: Quantum rings; thermal noise; phase-coherent transport; Aharonov-Bohm oscillations